Inhibition of tight junction molecules in human brain microvascular endothelial cells by methylmercury.

<p>Methylmercury is an environmental pollutant that causes central nervous system injury. Blood vessels are ubiquitous in the body and function to maintain homeostasis. Brain microvascular endothelial cells form a biological barrier called the blood-brain barrier (BBB). The BBB regulated by tight junction proteins in brain microvascular endothelial cells is essential in maintaining brain homeostasis because it separates brain tissue from the body circulation while selectively supplying nutrients and other substances. Loss of tight junction proteins has been linked to an increased BBB permeability. In addition, disruption of the integrity of this system has been associated with several central nervous system damages. In animal models, it has been suggested that methylmercury may cause BBB disorders, but the mechanism is unknown. In this study, we investigated the effect of methylmercury on the expression of tight junction molecules in brain microvascular endothelial cells (HBMECs) and we obtained the following results. (1) Methylmercury suppressed occludin and claudin-12 mRNA expression in HBMECs. (2) Methylmercury suppressed occludin protein expression in HBMECs. These results suggest that methylmercury interrupts tight junction through the suppression of occludin expression in HBMECs.</p>